Up to the present, chainstay and seat stay pipes of bicycle frames are joined to a rear dropout body by adhesive agents.
However, utilizing only adhesive, the worker could not uniformly spread an adhesive agent on a joining part, so that the strength of the joint was insufficient.
To solve the above problem, the idea of Japanese patent application publication No. Sho 50-12935 was suggested.
The construction of the above-mentioned idea is fitted to uniformly shaped pipes joined to each other, but is not utilized to join chainstay and seat stay pipes to a rear dropout, because the pipes are taper-shaped.